diff --git a/Scripts/enhancer.py b/Scripts/enhancer.py
index 6393c983f..003c4401f 100644
--- a/Scripts/enhancer.py
+++ b/Scripts/enhancer.py
@@ -45,6 +45,10 @@ class Enhance(Frame):
 #
 # main
 
+if len(sys.argv) != 2:
+    print("Usage: enhancer file")
+    sys.exit(1)
+
 root = Tk()
 
 im = Image.open(sys.argv[1])
diff --git a/Scripts/thresholder.py b/Scripts/thresholder.py
index bfeebfa9f..87eaf2e1d 100644
--- a/Scripts/thresholder.py
+++ b/Scripts/thresholder.py
@@ -60,6 +60,10 @@ class UI(Frame):
 # --------------------------------------------------------------------
 # main
 
+if len(sys.argv) != 2:
+    print("Usage: thresholder file")
+    sys.exit(1)
+
 root = Tk()
 
 im = Image.open(sys.argv[1])